Georgia Secretary of State Brad Raffensperger decided Thursday to audit his own reelection in a statewide ballot review, an effort to show whether voting machines got the results right.

Raffensperger said he picked the secretary of state’s race for the audit because it had the largest margin of any statewide contest, with the Republican incumbent defeating Democrat Bee Nguyen by 9.3 percentage points, making the outcome easier to confirm.

By auditing a race that wasn’t particularly close, Raffensperger said election workers will have to check a relatively small number of ballots by hand to validate the results while they’re also preparing for a U.S. Senate runoff on Dec. 6.

“Today is about ensuring confidence in the outcome of our elections in Georgia,” Raffensperger said during a press conference at the state Capitol. “Audits are incredibly important in the process to reinforce the importance and primacy of the paper ballots.”

The close Senate race also wasn’t chosen for the audit because it doesn’t yet have a winner, meaning an audit wouldn’t be able to validate the outcome, according to state election officials. A state law passed in 2019 requires an audit of one statewide race after each general election.

Unlike Georgia’s first election audit after the 2020 presidential election, this ballot review won’t involve every single vote cast.

Two years ago, Raffensperger ordered a full audit of all 5 million ballots cast, which showed that Democrat Joe Biden had won by about 12,000 votes over Republican Donald Trump.

Starting next week, audit teams will manually check the human-readable text on printed ballots from a randomly selected sample in each county, then compare the results with numbers reported by the state’s optical scanning machines, which use QR codes printed on ballots to count them.

The audit will involve between 5% and 7% of votes cast, totaling up to 300,000 ballots, a number designed to give a 95% statistical confidence level that the outcome was correct.

“It will show that the outcome of the election was correct, and it will also show that the machines that tabulated the votes worked properly,” State Elections Director Blake Evans said. “We want folks to know that we are trustworthy and the machines are trustworthy.”

Critics of Georgia’s voting machines, manufactured by Dominion Voting Systems, say audits are meaningless because they wouldn’t necessarily detect whether someone had secretly tampered with voting computers. They say it’s possible for someone with inside access to manipulate QR codes, and few voters would have noticed whether the printed text had been altered as well.

Georgia officials say there’s no evidence that voting equipment has ever been manipulated during an election, and that machines are kept secure by local election officials. Even if someone gained access to a voting touchscreen or scanner, they say, it’s unlikely they could alter large numbers of votes since election components aren’t directly connected to each other.

The audit is planned to last two days, on Nov. 17 and Nov. 18, before Raffensperger certifies results on Nov. 25. The audit will be conducted with software from the same company used in Georgia two years ago, VotingWorks, a San Francisco-based nonprofit.

Results of the audit will be posted on the secretary of state’s website so members of the public can compare the audited human tallies with machine counts for the selected batches of ballots, Evans said. If there’s a significant discrepancy, election officials would then have to audit a larger sample of ballots.